Abstract
We investigated the magnetocaloric and electrical transport properties of the Eu(8)CuNi(2.5)Si(42.5) clathrate compound, synthesized by an arc melting and annealing method. X-ray photoemission spectroscopy revealed a mixed valence state of Eu(2+) and Eu(3+). The low-field and low-temperature magnetic measurements indicated a multiple magnetic transition, from ferromagnetic near 35 K to antiferromagnetic at 25 K. Increasing the magnetic field led to the broadening of antiferromagnetic peaks and a final ferromagnetic state under high magnetic fields, indicative of spin reorientation. The transition from a ferromagnetic to an antiferromagnetic state was further corroborated by specific heat measurements. We noted spontaneous magnetization at low temperatures via magnetic hysteresis and Arrott plot analysis. The coexistence of an antiferromagnetic ground state (attributed to the Eu(2+) ions) and ferromagnetic clusters (associated with the Ni(2+) ions) was supported by spontaneous magnetization at low temperatures in the antiferromagnetic state. The magnetocaloric analyses revealed a high spin entropy change over a broad temperature range for Eu(8)CuNi(2.5)Si(42.5), which implies its potential as a robust low-temperature magnetocaloric material, distinguished by its high refrigerant capacity.